Compound A, , was found to be optically active. On catalytic reduction over a palladium catalyst, 2 equivalents of hydrogen were absorbed to yield compound B. Ozonolysis of A gave two compounds. One was identified as acetaldehyde, . The other compound, C, was an optically active dialdehyde, . Compound A has _____ chiral center(s) and compound B has _____ chiral center(s).